Metal expanding machine

ABSTRACT

A metal expanding machine for expanding of a workpiece of metal having rows of overlapping slots, the machine having workpiece tool supports thereon each carrying tools for securing a workpiece, and at least one of the tool supports being controlled by fluid actuated cylinders and so arranged that it is driven away from the other by means of the cylinders but at the end of its outward movement the cylinders are reversed to move a tool support back by an amount sufficient to relax the workpiece so that it can be readily removed from the tools.

[4 Oct. 7, 1975 1 METAL EXPANDING MACHINE [75] Inventors: Harold RexJury, Norwood; Ronald McKenzie Howells, Yennora, both of Australia [73]Assignee: Comalco (J. & S.) Pty. Limited,

Australia [22] Filed: Aug. 13, 1973 [21] Appl. No.: 387,703

[30] Foreign Application Priority Data Seifried 72/30 Kurtak 72/3023,070,147 12/1962 Schalich 72/26 3,109,350 11/1963 Wilson 29/6.l3,339,594 9/1967 Elliott 72/302 3,403,542 10/1968 BOVa 77/302 3,550,42012/1970 Swanson 72/296 3,774,274 11/1973 Jury 29/6.l

Primary Examiner-C. W. Lanham Assistant Examiner-M. J. Keenan Attorney,Agent, or Firm-Jay L. Chaskin, Esq.

[57] ABSTRACT A metal expanding machine for expanding of a workpiece ofmetal having rows of overlapping slots, the machine having workpiecetool supports thereon each carrying tools for securing a workpiece, andat least one of the tool supports being controlled by fluid actuatedcylinders and so arranged that it is driven away from the other by meansof the cylinders but at the end of its outward movement the cylindersare reversed to move a tool support back by an amount sufficient torelax the workpiece so that it can be readily removed from the tools.

15 Claims, 14 Drawing Figures U.S. Patent Oct. 7,1975 Sheet 1 of 73,910,092

US. Patent 0a. 7,1975 Sheet 2 of7 3,910,092

U.S. Patent Oct. 7,1975 Sheet 3 of7 3,910,092

I U.S. Patent Oct. 7,1975 Sheet4 0f7 3,910,092

US. Patent Oct. 7,1975 Sheet 5 of 7 3,910,092

U.S. Patent Oct. 7,1975 Sheet 6 of? 3,910,092

US. Patent Oct. 7,1975 Sheet 7 of7 3,910,092

METAL EXPANDING MACHINE This invention relates to a metal expandingmachine which is useful for the expansion of metal which contains slotsbetween adjacent beads so as to form a truss like member, or an expandedmesh.

BACKGROUND OF THE INVENTION Proposals have been put forward heretoforefor the formation of expanded metal wherein a strip of metal of constantthickness is sheared to have a series of rows of slits, the slits of anyone row being staggered with respect to those of the next adjacent row,and the metal edges are then drawn apart so as to bend the metal betweenadjacent slits, tilt them with respect to the plane of the metal beforebending, and form a mesh like panel. Such a panel has certain limitedapplications, but is not suitable for use as a load bearing memberprimarily because of the high stress concentrations at the ends of theslits and secondly because of the bending and displacement of the metalbetween adjacent slits.

This problem has been recognised and a number of proposals have beenmade to provide a member which is suitable, for example, for use as aload bearing member. Thus for example in the U.S. Pat. No. 1,510,702issued to Rendleman, a truss like metal beam was formed by firstlyforming slits between beads and then stretching those beads by passingthe section longitudinally over gradually diverging guides. Rendlemanalso teaches that a subsequent rolling operation may be employed if thisis desired. In the US. Pat. Nos. 1,510,697; 1,472,770; 1,472,771; and1,472,772, H. M. Naugle et al teach various methods of expanding a slitmetal member, all of which incorporate either the use of rollers or ofheat, and in some instances reference is made to the distortion of thebeads in a plane at right angles to the vertical plane of the product soas to obtain a preliminary stretching of the beads.

The US. Pat. No. 2,010,670 issued to Keller also refers to theproduction of an openwork structure from a member wherein a web has aseries of rows of staggered slits, but this also employs theconventional expanding guide. Again, the US. Pat. No. 1,927,442 issuedto Charles W. Laufle teaches the use of a wedge die which closelyembraces both the web and flanges causing the flanges to be separated.

While prior art means and methods have been suitable for very largeproduction of one size of open web structure, they have been quiteunsuitable for general purpose work, and the tooling cost is prohibitivewhen small production runs of different configurations are required froma single machine.

MAIN OBJECTS OF THE INVENTION A main object of this invention is toprovide a machine which is universal in its application for theexpansion of slotted metal members, so that it can be quickly and easilyadjusted from one configuration of expansion to another. A second objectis to avoid the need for expanding rollers to providea satisfactoryproduct, and a still further object is to provide a machine which can bequickly and easily loaded with a workpiece, which will then expand theworkpiece, and allow ready removal of the expanded workpiece.

BRIEF SUMMARY OF THE INVENTION Briefly the invention consists of anexpanding machine having a frame with longitudinal members and bearerswhich extend transversely, and which carry a tool support coupled to theframe by power actuated means, there being provided control memberswhich are actuated by abutment members carried on the movable toolsupport and arranged so that the power actuated means when actuated willfirstly move one tool support away from the other in transversedirection, thereby stretching a workpiece when secured to tools on thetool supports, but after the stretching has been completed, the poweractuated means reverse so that one tool support is then moved inwardlytowards the other, until a further abutment member carried by the toolsupport controls the power actuated means (after initial inward movementof the tool support) and tenninates actuation of the power actuatedmeans so that the workpiece is relaxed in its tools and can be readilyremoved therefrom. This then enables a workpiece to be quickly andeasily loaded into the machine and quickly and easily removed therefrom.Conveniently the degree of expansion can be adjusted by threadedmembers, although of course the first adjustable abutment member whicheffects reversal of actuation of the cylinders also functions as a meanswhich limits the expansion of a workpiece.

A machine constructed according to the invention can be utilised fordifferent configurations and diiferent degrees of expansion withrelatively simple tooling changeover and adjustment.

The invention also includes a method wherein a workpiece is firstlyexpanded, and is then relaxed before it is removed from the tools whichsecure its edges.

More specifically a machine according to the inven tion may be definedas a metal expanding machine which comprises a frame having alongitudinal member and bearers extending tranversely thereof, a pair ofspaced parallel workpiece tool supports supported by the bearers andextending in a longitudinal direction, workpiece engaging tools carriedby respective said tool supports and arranged to engage the longitudinaledge portions of a workpiece having a web between the edge portions anda series of rows of slots in the web, the slots of each row beingstaggered with respect to and overlapping the slots of at least oneadjacent row, power actuated means operatively coupling the toolsupports and arranged upon actuation to increase the transverse distancebetween the tool supports thereby expanding a workpiece when itslongitudinal edge portions are engaged by the tools, comprising a firstabutment member and a first control member operatively coupled to saidpower actuated means, one of the members being secured to the frame andthe other secured to the tool support and respectively positioned sothat at the end of said movement which increases the transverse distancebetween the tool supports said power actuating means is reversed toreduce said transverse distance, and a second abutment member cooperablewith a second control member respectively positioned so that aftersufficient reverse movement to relax tension in said expanded workpiecesaid expanded workpiece said reverse movement is terminated.

The method of expanding a workpiece comprises having a pair of spacedparallel edge portions, a web between the edge portions, a series ofrows of slots in the web, the slots of each row being staggered withrespect to and overlapping the slots of at least one adjacent row,comprising securing the parallel edge portions to tools carried onrespective workpiece tool supports driving the tool supports away fromone another to separate the edge portions and stretch those portions ofthe web between said staggered adjacent slots, driving the tool supportstowards one another by an amount sufficient to relax the stretched webportions,

and removing the expanded workpiece from the tools.

When a workpiece incorporates a series of rows of staggered slots, andis expanded by deforming so that the web portions between the edgeportions of the workpiece are stretched, the ends of the intermediateportions of the web which are not directly connected to the edgeportions are not subjected to strain as the edge portions are separated,and therefore the ends of the workpiece after stretching include shortlengths which are not of the same configuration as the intermediateportion of the stretched member. To avoid discarding these irregular endpieces, it is necessary to impart a stretching to the intermediate webportions, but it is found that constraining them against longitudinalinward movement (as the edge portions are moved apart transversely) iscompletely unsatisfactory in most instances, and greatly limits theexpansion of the workpiece.

Further, according to this invention, a metal expanding machine isprovided with respective workpiece clamps at each end of the frame,further pressure fluid actuated cylinders on the frame having theirpiston rods respectively coupled to said further workpiece clamps foreffecting movement of those further clamps in a longitudinal direction,and further control valves having conduit means coupling them to saidfurther pressure fluid actuated cylinders. This then enables the furtherworkpiece clamps to be clamped to the intermediate portions of aworkpiece, and for those intermediate portions to be stretched in alongitudinal direction after the main stretch jaws have been relaxed ina transverse direction to release the stress in the web.

This procedure is effective in achieving a consistent pattern over theentire workpiece.

BRIEF DESCRIPTION OF THE DRAWINGS of FIG. 1,

FIG. 3 is an end-elevational section taken on line 33 of FIG. 1,

FIG. 4 is also an end elevational section but taken on line 44 of FIG.1,

FIG. 5 is a plan view of a workpiece before stretching, showing the edgeportions, the web portions, and a series of rows of staggeredoverlapping slots which divide the web portion into a series ofstretchable portions,

FIG. 6 is a section taken on line 66 of FIG. 5,

FIG. 7 is a plan view which corresponds to FIG. 5 but showing theworkpiece after it has been stretched,

FIG. 8 is a section taken on line 88 of FIG. 7 but showing in additionto the workpiece, also the tools and tool supports utilised in thestretching thereof,

FIG. 9 is a section taken online 99 of FIG. I which illustrates the endclamps utilised for the secondary or longitudinal stretching of theworkpiece,

FIG. 10 is a fragmentary plan showing a mesh type workpiece wherein theweb portions are more bent than stretched during the expansion of theworkpiece, FIG. 11 is a section on line l11l of FIG. 10 but drawn to anenlarged scale,

FIG. 12 is an enlarged plan view illustrating the tool location afterexpanding of the workpiece illustrated in FIG. 10,

FIG. 13 is a fragmentary perspective illustrating locating means for thelocating of the tools shown in FIGS. 10, 11, and 12 before expansion ofthe workpiece, and

FIG. 14 is a diagrammatic representation of the hydraulic and electricalcontrol means for the machine.

In general, a metal expanding machine 20 comprises a frame 21 (shown inFIGS. 1, 2, 3 and 4) which has a single longitudinal member 22 of Isection, and bearers 23 which extend transversely of the longitudinalmember 22.

Workpiece tool supports 26 are carried by the bearers 23, resting uponthem, and these are coupled to the frame 21 by a plurality of pressurefluid actuated cylinders 27. It will be noted that in the embodimentdescribed both workpiece tool supports 26 are arranged to be moved overthe bearers, but it will be clear to those in the art that in manyinstances only one need be movable, and one of the workpiece toolsupports can be fixed to the frame 20. The means which couple thecylinders 27 to the frame 20 comprise trunnion blocks 28 describedhereunder in further detail, and which enable limited relative pivotalmovement of the cylinders 27 to take place.

The valve means are not illustrated in the physical drawings of FIGS. 1,2, 3 or 4, but are shown diagrammatically in FIG. 14 as a single valve30 (in practice use may be made of more than one valve) the single valve30 being a solenoid operated valve and being connected by pressure fluidconduits 31 to the cylinders 27 so that operation of the valve 30 willeffect actuation of the cylinders 27.

The frame 21 has secured to it valve control means, a first valvecontrol means being a limit switch 33, attached to a transverse bearer23, (shown in FIGS. 1 and 14) which is operated by an adjustableabutment member 34 carried on an arm 35 on the workpiece tool support26, and a second valve control means comprises a second limit switch 37,also attached to transverse bearer 23, which is functional to reverseoperation of the valve 30. This is actuated by a second adjustableabutment member 38 also carried on the arm 35, the abutment member 38having on it a swinging arm 39 arranged so that the second limit switch37 is actuated only upon reversal of movement (that is in an inwarddirection) of the workpiece tool support 26. The valve 30 is furthercontrolled by hand operated valve control means in the form of the twopush button switches designated 41 and 42 in FIG. 14 (but not shownelsewhere), and it will be seen from FIG. 14 that one of these switchesis effective in causing continued inward actuation of the cylinders 27,actuation of which had previously been arrested by the limit switch 37.Operation of the second button 42 will be seen to initiate the outwardstroke of the respective cylinders 27.

After a workpiece has been expanded, it will be noted that the ends ofsome of the web portions not directly connected with the edge portionshave not been themselves stretched (see FIG. 7) and to avoid wastage ofmaterial it is desirable to separately stretch those intermediateportions. To this end, the machine is pro vided with workpiece endclamps designated 45, these being under the control of further pressurefluid actuated cylinders designated 46 and referred to as end stretchcylinders, the cylinders 46 being trunnion mounted on brackets 47 whichextend outwardly from the frame 21 at respective ends. These arecontrolled by further control valves (not herein illustrated) which maybe hand operated or electrically operated but are continuously underoperator control. No automatic termination of actuation of the cylinders46 is incorporated in this embodiment, although if desired the automaticcontrol of the cylinders 27 may be duplicated for this purpose. I

The above description is a description of the main elements of theinvention, but the embodiment is de' scribed hereunder in further detailas follows:

Each of the cylinders 27 is trunnion mounted in a trunnion mount blockdesignated 28 in FIGS. 1 and 3, the trunnion block 28 also havingtrunnion mounted therein a threaded rod 49 which carries on it two pairsof nuts 50, the arrangement being such that the nuts 50 abut therespective trunnion blocks 28 at the inner or outer end of stroke of therespective cylinders 27. This provides a positive termination of stroke,and the adjustable abutment member 34 is so adjusted that reversal ofthe valve 30 does not take place until the termination of stroke asfixed by the nuts 50. There are occasions when it is desirable for theworkpiece to be stretched so that the final product has tapered sidesinstead of parallel sides, and this can be readily achieved with thearrangement described herein by mere adjustment of the nuts 50 sinceboth the cylinders 27 and the threaded rods 29 are trunnion mounted andare pivotally mounted onto respective brackets 51 on the workpiecesupport 26. 1

FIGS. 5, 6, 7 and 8 illustrate workpieces before and after expansioneffected by stretching. In FIGS. 5 and 6 an extrusion of an aluminiumalloy (or other ductile extrusile material) designated 54 is providedwith edge flanges 55, and a web 56 extending between them. The web isitself formed to have three beads 57, and the web is separately piercedto have a series of rows of slots 58 (four rows being shown) the slotsof each row being staggered with respect to and overlapping the slots ofeach adjacent row. (In some cases, the rows are divided into pairs ofrows of adjacent slots wherein the slots are staggered, but the adjacentrows of adjacent pairs have the slots in transverse alignment).

FIG. 8 illustrates how the workpiece is clamped between tools designated61 which are carried on respective workpiece tool supports 26. The lowerof the tool supports 26 is coupled directly to the piston rods of thecylinders 27 through the brackets 51 as described above, but the uppertool supports 26 are pivoted on pivot pins 62 (see particularly FIGS. 3and 4), and are arranged to be lifted upwardly and outwardly from thelower tool supports 26 by means of tool clamp cylinders 63, pivotallyattached to the lower tool support 26 and coupled to the upper toolsupports 26 by means of lever arm 64 and coupling links 65.

In order to limit distortion of the flanges 55 of the workpiece 54, itis desirable that these flanges be clamped in place, so that use is made(in addition to the tool clamp cylinder 63) of back clamp cylinders 68.One back clamp cylinder is trunnion mounted to each of the tool supports26, and the clamping of the flanges is effected by longitudinallymovable clamp bars 69 which are coupled to the lower of the toolsupports 26 by a plurality of short swinging links designated 70, eachlink 70 being pivoted at one end to a tool support and at the other to aclamp bar. This arrangement then provides means for quickly loading andunloading the workpiece, and clamping the workpiece flanges. The controlmeans for the cylinders are their respective valves 73 (for cylinder 63)and 74 (for cylinder 68), these valves being solenoid operated valves.The valve 74 is controlled inter alia by :a limit switch designated 75(shown only in FIG. 14), the limit switch 75 being co-operable toreverse the valve 74 when the workpiece is to be loaded or unloaded.This then is a standard cam operated limit switch butfor simplicity ofillustration this has not been shown in FIG. 1. The cylinders 63 areeither hand operated by a means of the switch designated 76, oralternatively timer operated by means of the timer designated 77. Thefunction of the timer is described hereunder with respect to thestretching of mesh material.

Referring further to FIG. 14., an electric motor designated ismechanically coupled to two pumps, the pump designated 81 feeding themain stretching cylinders 27, the pump designated 82 feeding only theclamping cylinders 63 and 68. In both cases there is an overload valve(both being designated 84) to protect the equipment against overpressure. (In practice there are two other tandem pumps, effectingindependent control of the stretch cylinders, clamp cylinder 68, and endstretch cylinders. For the sake of simplicity these are notillustrated.)

A reference to FIG. 7 will illustrate how the intermediate beads whichare designated 87 and which are not directly connected to the edgeflanges 55 are not stretched as the other beads are stretched uponseparation of the edge flanges 55, and to effect the required stretchthe workpiece end clamps 45 are utilised. In FIG. 7 there are two onlyintermediate beads 87, and these are joined with a web portion 56 asshown. In FIG. 1 a more complicated arrangement is shown whereby it isnecessary to elongate four pairs of intermediate beads 87 (not shown),and this is achieved by means of the end clamps 45 operated by the endstretch cylinders 46. The end stretch cylinders 46 are trunnion mountedso that normally they do not constitute an obstruction to the loading ofworkpieces in the machine. However they may be swivelled upwardly sothat the wedge clamp members 89 (FIG. 9) lie in the same plane as theintermediate beads to be stretched, whereupon the cylinder 46 may beactuated to move the wedge clamps inwardly and over the beads to bestretched. Each pair of wedge clamps 89 is carried in a clamping block90, and the clamping blocks are interconnected by means of toggle links91, the toggle links being themselves connected to adjustable mountingblocks 92 by means of tension bars 93, and the arrangement is such thatas the tension bars 93 are drawn rearwardly, the toggle links 91 becomeco-linear, and are retained in their co-linear positions by means ofabutment extensions designated 94 which interengage one another. Thisthen correctly positions the pairs of beads 87 (which otherwise tend tobe too close to one another). The gaps between the respective beads areengaged by the pins 96 (FIG. 9) to further effect the accurate locationof the pairs of beads. The mounting blocks 92 are adjustably positionedin a cross-bar 97, by means of bolts 98 the heads of which lie in a Tslot 99.

The wedge clamp members 89 are urged against ramp faces in a clampingblock 90 by springs 102, but these springs may be compressed and theblocks 89 urged into engagement with the end of a workpiece by operationof a release handle 103, each handle rocking about a pin 104, and havinga finger 105 thereon which abuts the ends of blocks 89. Release ofhandle 103 allows the springs to expand and cause the space between theblocks 89 to increase. During the application of longitudinal stretch bycylinders 46, blocks 89 tend to move along the ramp face towards oneanother and thereby more firmly grip the workpiece. This is bestillustrated in FIG. 9.

The FIGS. 10, 11, 12 and 13 illustrate the means and method by which themachine is used for expanding material to a mesh shape, wherein thebeads or web portions 57 are bent rather than stretched. Bending(without appreciable stretching) can take place only if the length ofthe mesh panel is allowed to contract as the width increases, and thisis effected by securing to the lower workpiece tool support 26 a trackdesignated 110 containing a slot 111 which guides and supports rollers112 on carriage blocks 113, each carriage block 113 having clamped to ita support hook 114 which engages the edge of a mesh panel (that isportion of the bead 57) as shown in FIG. 11. There are a series ofcarriage blocks 113 arranged in line in each of the tracks, and thecentre carriage block is fixed. the others being movable with respect tothat carriage block. They are interconnected by a flexible linedesignated 116, which when stretched taut maintains them in an equallyspaced position. To accurately fix those positions, the upper of the twoworkpiece tool supports 26 is provided with an outstanding cam plate 117as illustrated in FIG. 13, and recesses 118 in the cam plate 117 engageover respective carriage blocks 113 so that the surfaces of recesses 118form abutment surfaces which accurately position them, this enabling theworkpiece to be engaged on the hooks 114. To ensure that the finalproduct has a consistent pattern throughout its entire area, the blocks113 are formed of such length that they abut one another at thetermination of formation of the panel from the workpiece. As the books114 move towards one another, the flexible line 116 flexes illustratedin FIG. 12.

The following is a summary of the sequence of operations when aworkpiece is to be expanded by stretching (FIGS. 1 through to 9):

A. All pumps idling, sliding clampjaws at their innermost position withclamp jaws open and back-up clamp released.

B. Slotted section loaded either from the end or above.

C. Clamp jaws and back-up clamp close by manual switching.

D. Stretch cycle initiated. Stretch cycle completed. Jaws relaxed sothat no stress is left on the section being processed. All valves arecentred so that the main stretch cylinders are locked at this point.

E. End stretch mechanism operated and detached.

F. Strain released from main stretch cylinders (by manual switching).

G. Back-up clamp and clamp jaws released (by manual switching).

H. Stretched product unloaded.

1. Machine reset.

The following summary is a sequence of operations when the workpiece isto be expanded by bending (FIGS. 10 through to 13):

Machine changed from a stretching to a bending cycle by a resettingselector switch (not shown herein).

A. All pumps idling. Section engaging hooks positioned and retained bylocation plate 118.

B. Preslotted extrusion placed on hooks.

C. Bending cycle initiated. Timer delays main stretch cylinders untillocation plate 118 has retracted, then bending cycle carried out to thereleased position.

D. Mesh unloaded.

E. Hooks reset by manual switching of top jaw and location plate 118.

F. Machine reset.

What we claim is:

1. A metal expanding machine for the expanding of a workpiece havingspaced parallel edge portions, comprising:

a frame having a longitudinal member and bearers extending transverselythereof,

a pair of spaced parallel workpiece tool supports supported by thebearers and extending in a longitudinal direction,

workpiece engaging tools carried by respective said tool supports andarranged to engage the longitudinal edge portions of a workpiece havinga web between the edge portions and a series of rows of slots in theweb, the slots of each row being staggered with respect to andoverlapping the slots of at least one adjacent row,

power actuated means operatively coupling the tool supports and arrangedupon actuation to increase the transverse distance between the toolsupports thereby expanding a workpiece when its longitudinaledgeportions are engaged by the tools, comprising a first abutment memberand a first control member operatively coupled to said power actuatedmeans, one of the members being secured to the frame and the othersecured to the tool support and respectively positioned so that at theend of said movement which increases the transverse distance between thetool supports said power actuating means is reversed to reduce saidtransverse distance, and

a second abutment member co-operable with a second control memberrespectively positioned so that after sufficient said reverse movementto relax tension in said expanded workpiece said reverse movement isterminated.

2. A metal expanding means according to claim 1 wherein said poweractuated means operatively coupling the tool supports comprise aplurality of pressure fluid actuated cylinders, a solenoid operatedvalve having three positions, and arranged so that upon energizing oneof two solenoids the cylinders are actuated to move the tool supportoutwardly; upon energizing the other solenoid the cylinders are actuatedto move the tool support inwardly; and upon deenergising both solenoidsthe cylinders become inactive,

said first and second valve control members comprising respective limitswitches secured to the frame, and operatively coupled to respectivesaid solenoids, said adjustable abutment members being limit switchoperating pawls.

3. A metal expanding means according to claim 1 wherein each saidworkpiece tool support is a movable tool support, and wherein there aretwo rows of said cylinders, each tool support comprising a horizontallymovable portion fixed to the piston rods of a respective said row ofcylinders and a pivoted portion, pivot means coupling the pivotedportion to the horizontally movable portion, and further comprisingclamping tools secured to respective tool support portions of each toolsupport, further pressure fluid actuated cylinders constituting toolclamp cylinders and operatively coupling the horizontally movable andpivoted portions of each tool support for the effecting of clamping ofthe workpiece edge portions between respective pairs of said tools.

4. A metal expanding means according to claim 1 further comprising apair of clamp bars, a series of swinging links coupling each clamp barto a respective said workpiece tool support for effecting movement ofthe clamp bars in a horizontal plane. and respective further pressurefluid actuated cylinders operatively coupling the clamp bars to therespective workpiece for effecting movement of the clamp bars from outerpositions inwardly towards the tools on the respective workpiece.

5. A metal expanding means according to claim 1 comprising a furtherpair of workpiece end clamps positioned one at each end of the frame,and further pressure fluid actuated cylinders constituting end stretchcylinders operatively cotp ling the workpiece end clamps to respectiveends of the frame.

6. A metal expanding means according to claim wherein each said endstretch cylinder has a trunnion mounting joining it to the respectivesaid end of the frame.

7. A metal expanding means according to claim 5 wherein each saidworkpiece end clamp comprises a pair of wedge clamp members slidable ina clamping block, and arranged to engage converging surfaces in theclamping block to thereby cause the wedge clamp members to firmly grip aworkpiece with which they are engaged upon movement of the mountingblock.

8. A metal expanding means according to claim 3 further comprising apair of tracks, means securing the tracks to respective saidhorizontally movable portions of the tool support, a series of carriageblocks, rollers on each said carriage block engaging surfaces in a saidtrack, a flexible line interconnecting the carriage blocks carried byeach respective said track, and an inwardly directed workpiece engaginghook on each said carriage block.

9. A metal expanding means according to claim 5 further comprising a camplate on the pivoted portion of each said respective tool support, eachcam plate having a series of abutment surfaces each being arranged toposition a respective hook and being so positioned that pivotal movementof the cam plate when effected by operation of said tool clamp cylinderspositions said carriage blocks in an equally spaced relationship fromone another.

10. A metal expanding means according to claim 5 wherein each saidworkpiece end clamp comprises a pair of wedge clamp members slidable ina mounting block, and arranged to engage outwardly converging surfacesin .the mounting block to thereby cause the wedge clamp members tofirmly grip a workpiece with which they are engaged upon outwardmovement of the mounting block, and further comprising a series oftoggle links interconnecting the workpiece end clamps at each end of theframe, a cross bar secured to the piston rod of each respective eachsaid end stretch cylinder and tension bars joining respective saidmounting blocks at each end of the frame to a said cross bar.

11. A metal expanding means according to claim 3 further comprising apair of tracks, means securing the tracks to respective saidhorizontally movable portions of the tool support, a series of carriageblocks, rollers on each said carriage block engaging surfaces in a saidtrack, a flexible line interconnecting the carriage blocks carried byeach respective said track, and an inwardly directed workpiece engaginghook on each said carriage block, and wherein the lengths of thecarriage blocks are equal, and also equal the pitch of a workpiece afterit is expanded, the carriage blocks being positionable in end to endabutment.

12. A metal expanding means according to claim 5 further comprising acam plate on the pivoted portion of each said respective tool support,each cam plate having a series of tapered mouth recesses each being ofsize to accommodate a respective hook between its side edges and beingso positioned that downward pivotal movement of the cam plate wheneffected by operation of said tool clamp cylinders positions saidcarriage blocks in an equally spaced relationship from one another, afurther solenoid operated valve, further pressure fluid conduitscoupling said further valve to said tool clamp cylinders, a hand controlswitch and a timer control switch both interconnected with said furthersolenoid operated valve and arranged to independently complete anenergising circuit therefor.

13. A method of expanding a workpiece having a pair of spaced paralleledge portions, a web between the edge portions, a series of rows ofslots in the web, the slots of each row being staggered with respect toand overlapping the slots of at least one adjacent row, comprising,

securing the parallel edge portions to tools carried on respectiveworkpiece tool supports;

driving the tool supports away from one another to separate the edgeportions and stretch those portions of the web between said staggeredadjacent slots;

driving the tool supports towards one another by an amount sufficient torelax the stretched web portions;

engaging the ends of said web portions with wedge clamp members;

applying fluid at pressure to cylinders coupled to said wedge clampmembers to thereby actuate those cylinders and in turn elongate said webportions. releasing the wedge clamp members from the workpiece;

and then removing said workpiece from the tools.

14. A method according to claim 13 wherein said securing of the elongateportions of the workpiece to respective said tools comprises clampingsaid edge portions between the tools, and said deforming of the webportions comprises stretching and bending of the web portions.

15. A method according to claim 13 wherein said se curing of the edgeportions of the workpiece to respecare movable along a track, movingsaid tool supports away from one another to thereby bend said portionsand simultaneously move the carriageblocks towards one another, and theneffecting said relaxing and retive said tools comprises positioningedges of the workmoving of the workpiece from the tools.

piece over hooks on respective carriage blocks which

1. A metal expanding machine for the expanding of a workpiece havingspaced parallel edge portions, comprising: a frame having a longitudinalmember and bearers extending transversely thereof, a pair of spacedparallel workpiece tool supports supported by the bearers and extendingin a longitudinal direction, workpiece engaging tools carried byrespective said tool supports and arranged to engage the longitudinaledge portions of a workpiece having a web between the edge portions anda series of rows of slots in the web, the slots of each row beingstaggered with respect to and overlapping the slots of at least oneadjacent row, power actuated means operatively coupling the toolsupports and arranged upon actuation to increase the transverse distancebetween the tool supports thereby expanding a workpiece when itslongitudinal edge portions are engaged by the tools, comprising a firstabutment member and a first control member operatively coupled to saidpower actuated means, one of the members being secured to the frame andthe other secured to the tool support and respectively positioned sothat at the end of said movement which increases the transverse distancebetween the tool supports said power actuating means is reversed toreduce said transverse distance, and a second abutment memberco-operable with a second control member respectively positioned so thatafter sufficient said reverse movement to relax tension in said expandedworkpiece said reverse movement is terminated.
 2. A metal expandingmeans according to claim 1 wherein said power actuated means operativelycoupling the tool supports comprise a plurality of pressure fluidactuated cylinders, a solenoid operated valve having three positions,and arranged so that upon energizing one of two solenoids the cylindersare actuated to move the tool support outwardly; upon energizing theother solenoid the cylinders are actuated to move the tool supportinwardly; and upon deenergising both solenoids the cylinders becomeinactive, said first and second valve control members comprisingrespective limit switches secured to the frame, and operatively coupledto respective said solenoids, said adjustable abutment members beingliMit switch operating pawls.
 3. A metal expanding means according toclaim 1 wherein each said workpiece tool support is a movable toolsupport, and wherein there are two rows of said cylinders, each toolsupport comprising a horizontally movable portion fixed to the pistonrods of a respective said row of cylinders and a pivoted portion, pivotmeans coupling the pivoted portion to the horizontally movable portion,and further comprising clamping tools secured to respective tool supportportions of each tool support, further pressure fluid actuated cylindersconstituting tool clamp cylinders and operatively coupling thehorizontally movable and pivoted portions of each tool support for theeffecting of clamping of the workpiece edge portions between respectivepairs of said tools.
 4. A metal expanding means according to claim 1further comprising a pair of clamp bars, a series of swinging linkscoupling each clamp bar to a respective said workpiece tool support foreffecting movement of the clamp bars in a horizontal plane, andrespective further pressure fluid actuated cylinders operativelycoupling the clamp bars to the respective workpiece for effectingmovement of the clamp bars from outer positions inwardly towards thetools on the respective workpiece.
 5. A metal expanding means accordingto claim 1 comprising a further pair of workpiece end clamps positionedone at each end of the frame, and further pressure fluid actuatedcylinders constituting end stretch cylinders operatively coupling theworkpiece end clamps to respective ends of the frame.
 6. A metalexpanding means according to claim 5 wherein each said end stretchcylinder has a trunnion mounting joining it to the respective said endof the frame.
 7. A metal expanding means according to claim 5 whereineach said workpiece end clamp comprises a pair of wedge clamp membersslidable in a clamping block, and arranged to engage converging surfacesin the clamping block to thereby cause the wedge clamp members to firmlygrip a workpiece with which they are engaged upon movement of themounting block.
 8. A metal expanding means according to claim 3 furthercomprising a pair of tracks, means securing the tracks to respectivesaid horizontally movable portions of the tool support, a series ofcarriage blocks, rollers on each said carriage block engaging surfacesin a said track, a flexible line interconnecting the carriage blockscarried by each respective said track, and an inwardly directedworkpiece engaging hook on each said carriage block.
 9. A metalexpanding means according to claim 5 further comprising a cam plate onthe pivoted portion of each said respective tool support, each cam platehaving a series of abutment surfaces each being arranged to position arespective hook and being so positioned that pivotal movement of the camplate when effected by operation of said tool clamp cylinders positionssaid carriage blocks in an equally spaced relationship from one another.10. A metal expanding means according to claim 5 wherein each saidworkpiece end clamp comprises a pair of wedge clamp members slidable ina mounting block, and arranged to engage outwardly converging surfacesin the mounting block to thereby cause the wedge clamp members to firmlygrip a workpiece with which they are engaged upon outward movement ofthe mounting block, and further comprising a series of toggle linksinterconnecting the workpiece end clamps at each end of the frame, across bar secured to the piston rod of each respective each said endstretch cylinder and tension bars joining respective said mountingblocks at each end of the frame to a said cross bar.
 11. A metalexpanding means according to claim 3 further comprising a pair oftracks, means securing the tracks to respective said horizontallymovable portions of the tool support, a series of carriage blocks,rollers on each said carriage block engaging surfaces in a said track, aflexible line interconnecting the carriage blocks carried by eachrespective said track, and an inwardly directed workpiece engaging hookon each said carriage block, and wherein the lengths of the carriageblocks are equal, and also equal the pitch of a workpiece after it isexpanded, the carriage blocks being positionable in end to end abutment.12. A metal expanding means according to claim 5 further comprising acam plate on the pivoted portion of each said respective tool support,each cam plate having a series of tapered mouth recesses each being ofsize to accommodate a respective hook between its side edges and beingso positioned that downward pivotal movement of the cam plate wheneffected by operation of said tool clamp cylinders positions saidcarriage blocks in an equally spaced relationship from one another, afurther solenoid operated valve, further pressure fluid conduitscoupling said further valve to said tool clamp cylinders, a hand controlswitch and a timer control switch both interconnected with said furthersolenoid operated valve and arranged to independently complete anenergising circuit therefor.
 13. A method of expanding a workpiecehaving a pair of spaced parallel edge portions, a web between the edgeportions, a series of rows of slots in the web, the slots of each rowbeing staggered with respect to and overlapping the slots of at leastone adjacent row, comprising, securing the parallel edge portions totools carried on respective workpiece tool supports; driving the toolsupports away from one another to separate the edge portions and stretchthose portions of the web between said staggered adjacent slots; drivingthe tool supports towards one another by an amount sufficient to relaxthe stretched web portions; engaging the ends of said web portions withwedge clamp members; applying fluid at pressure to cylinders coupled tosaid wedge clamp members to thereby actuate those cylinders and in turnelongate said web portions, releasing the wedge clamp members from theworkpiece; and then removing said workpiece from the tools.
 14. A methodaccording to claim 13 wherein said securing of the elongate portions ofthe workpiece to respective said tools comprises clamping said edgeportions between the tools, and said deforming of the web portionscomprises stretching and bending of the web portions.
 15. A methodaccording to claim 13 wherein said securing of the edge portions of theworkpiece to respective said tools comprises positioning edges of theworkpiece over hooks on respective carriage blocks which are movablealong a track, moving said tool supports away from one another tothereby bend said portions and simultaneously move the carriage blockstowards one another, and then effecting said relaxing and removing ofthe workpiece from the tools.